Image sensor

ABSTRACT

An image sensor and a method for fabricating the same are provided, in which the image sensor includes a substrate including a first sensing region having a photoelectric device therein, a boundary isolation film partitioning the first sensing region, an inner reflection pattern film within the substrate in the sensing region, an infrared filter on the substrate, and a micro lens on the infrared filter.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application based on pending application Ser. No.15/666,907, filed Aug. 2, 2017, the entire contents of which is herebyincorporated by reference.

Korean Patent Application No. 10-2017-0014560 filed on Feb. 1, 2017 inthe Korean Intellectual Property Office, and entitled: “Image Sensor andMethod for Fabricating the Same,” is incorporated by reference herein inits entirety.

BACKGROUND 1. Field

The present disclosure relates to an image sensor and a method forfabricating the same.

2. Description of the Related Art

An image sensor converts an optical image into an electric signal. Acomplementary metal oxide semiconductor (CMOS) image sensor (CIS)includes a plurality of 2-dimensionally arranged pixels. Each of thepixels includes a photodiode to convert an incident light into anelectric signal.

In recent years, according to development in the computer and thecommunication industries, demand has increased for the image sensorswith enhanced performances in a variety of fields such as digitalcameras, camcorders, personal communication systems (PCS), gamingdevices, security cameras, medical micro cameras, robots, and so on.Further, highly-integrated semiconductor devices have enabled highintegration of image sensors.

SUMMARY

According to an embodiment, there is provided an image sensor, includinga substrate having a first sensing region with a photoelectric devicetherein, a boundary isolation film to partition the first sensingregion, an inner reflection pattern film within the substrate in thesensing region, an infrared filter on the substrate and a micro lensformed on the infrared filter.

According to another embodiment, there is provided an image sensor,including a substrate having first and second sensing regions, eachhaving a photoelectric device therein, a boundary isolation filmdefining a boundary of the first and second sensing regions, an innerreflection pattern film formed within the substrate in the secondsensing region, a first filter formed on the first sensing region of thesubstrate, a second filter formed on the second sensing region of thesubstrate, wherein the second filter is different from the first filter,a first micro lens formed on the first filter and a second micro lensformed on the second filter.

According to still another embodiment, there is provided an imagesensor, including a substrate including first and second surfacesopposite each other and a first sensing region, and having aphotoelectric device therein, an insulating structure on the firstsurface and including a wire structure, a boundary isolation film on thesecond surface into the substrate and defining the first sensing region,an inner reflection pattern film formed within the first sensing regioninto the substrate, and including a same material as the boundaryisolation film, a filter on the second surface that transmits only lightof a certain wavelength and a micro lens formed on the filter.

According to an embodiment, there is provided a method for fabricatingan image sensor, including providing a substrate having first and secondsurfaces opposite each other, wherein the substrate includes aphotoelectric device therein, forming an insulating structure includinga wire structure on the first surface, forming a boundary isolation filmdefining a sensing region of the substrate, forming an inner reflectionpattern film within the sensing region and forming a filter and a microlens on the second surface.

According to an embodiment, there is provided an image sensor, includinga substrate including infrared and color sensing regions each having aphotoelectric device therein, a boundary isolation film defining aboundary of the infrared and color sensing regions, an inner reflectionpattern film within the substrate in the infrared region, a color filteron the color sensing region of the substrate, and an infrared filter onthe infrared sensing region of the substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

Features will become apparent to those of skill in the art by describingin detail exemplary embodiments with reference to the attached drawingsin which:

FIG. 1 illustrates a block diagram of an image sensor according to someexemplary embodiments.

FIG. 2 illustrates an equivalent circuit diagram of the sensor array ofFIG. 1.

FIG. 3 illustrates a layout diagram provided to explain an image sensoraccording to some exemplary embodiments.

FIG. 4 illustrates a cross-sectional view taken on line A-A′ of FIG. 3.

FIG. 5 illustrates a concept view provided to explain operation wheninfrared light is incident on the sensor shown in FIG. 4.

FIG. 6 illustrates a layout diagram provided to explain an image sensoraccording to some exemplary embodiments.

FIG. 7 illustrates a layout diagram provided to explain an image sensoraccording to some exemplary embodiments.

FIG. 8 illustrates a layout diagram provided to explain an image sensoraccording to some exemplary embodiments.

FIG. 9 illustrates a cross-sectional view provided to explain an imagesensor according to some exemplary embodiments.

FIG. 10 illustrates a cross-sectional view provided to explain an imagesensor according to some exemplary embodiments.

FIG. 11 illustrates a layout diagram provided to explain an image sensoraccording to some exemplary embodiments.

FIG. 12 illustrates a cross-sectional view taken on line B-B′ of FIG.11.

FIG. 13 illustrates a concept view provided to explain operation wheninfrared light is incident on the sensor shown in FIG. 12.

FIG. 14 illustrates a layout diagram provided to explain an image sensoraccording to some exemplary embodiments.

FIG. 15 illustrates a layout diagram provided to explain an image sensoraccording to some exemplary embodiments.

FIG. 16 illustrates a cross-sectional view taken on line C-C′ of FIG.15.

FIG. 17 illustrates a layout diagram provided to explain an image sensoraccording to some exemplary embodiments.

FIGS. 18 to 24 illustrate views of stages in a method for fabricating animage sensor according to some exemplary embodiments.

FIGS. 25 to 28 illustrate views of stages in a method for fabricating animage sensor according to some exemplary embodiments.

DETAILED DESCRIPTION

Hereinafter, an image sensor according to some exemplary embodimentswill be described with reference to FIGS. 1 to 5. FIG. 1 is a blockdiagram provided to explain an image sensor according to some exemplaryembodiments, and FIG. 2 is an equivalent circuit diagram of the sensorarray in FIG. 1. FIG. 3 is a layout diagram provided to explain an imagesensor according to some exemplary embodiments, and FIG. 4 is across-sectional view taken on line A-A′ of FIG. 3. FIG. 5 is a conceptview provided to explain operation when infrared light is incident onthe sensor shown in FIG. 4.

Referring to FIG. 1, an image sensor according to some exemplaryembodiments includes a sensor array 10, a timing generator 20, a rowdecoder 30, a row driver 40, a correlated double sampler (CDS) 50, ananalog to digital converter (ADC) 60, a latch 70, a column decoder 80,and so on.

The sensor array 10 includes a plurality of 2-dimensionally arrangedunit pixels. The plurality of unit pixels converts an optical image intoan electric output signal. The sensor array 10 receives a plurality ofdriving signals including row-select signal, reset signal, chargetransfer signal, and so on, and is driven accordingly. Further, theconverted electric output signal is provided to the correlated doublesampler 50 through vertical signal lines.

The timing generator 20 provides a timing signal and a control signal tothe row decoder 30 and the column decoder 80.

The row driver 40 provides the sensor array 10 with a plurality ofdriving signals to drive a plurality of unit pixels according to aresult of decoding at the row decoder 30. Generally, the driving signalsare provided to each of the rows when the unit pixels are arranged in amatrix form.

The correlated double sampler 50 receives an output signal from thesensor array 10 through a vertical signal line, and holds and samplesthe received signal. That is, the correlated double sampler 50double-samples a certain noise level and a signal level according to theoutput signal, and outputs a difference level corresponding to adifference between the noise level and the signal level.

The analog to digital converter 60 converts an analog signalcorresponding to the difference level into a digital signal, and outputsthe result of conversion.

The latch 70 latches the digital signal, and the latched signal isoutput to an image signal processor sequentially according to the resultof decoding at the column decoder 80.

Referring to FIG. 2, pixels P are arranged into a matrix pattern toconstruct the sensor array 10. Each of the pixels P includes aphotoelectric transistor 11, a floating diffusion region 13, a chargetransfer transistor 15, a drive transistor 17, a reset transistor 18,and a select transistor 19. These functions will be described withreference to i-th row pixel (P(i, j), P(i, j+1), P(i, j+2), P(i, j+3), .. . ) as an example.

The photoelectric transistor 11 absorbs the incident light andaccumulates charges corresponding to a quantity of the light. For thephotoelectric transistor 11, a photodiode, a phototransistor, aphotogate, a pinned photodiode or a combination thereof may be applied,although the photodiode is illustrated in the drawings as an example.

Each of the photoelectric transistors 11 is coupled with each of thecharge transfer transistors 15 that transfer the accumulated charges tothe floating diffusion region 13. The floating diffusion region 13 is aregion where the charges are converted into voltages, and because of theparasitic capacitance, the charges are accumulatively stored.

The drive transistor 17, exemplified herein as a source followeramplifier, amplifies a change in the electric potential of the floatingdiffusion region 13 transmitted with the accumulated charges of each ofthe photoelectric transistors 11, and outputs the amplified result to anoutput line Vout.

The reset transistor 18 periodically resets the floating diffusionregion 13. The reset transistor 18 may be composed of one MOS transistorthat is driven by the bias provided from a reset line RX(i) for applyinga predetermined bias (i.e., reset signal). When the reset transistor 18is turned on by the bias provided from the reset line RX(i), apredetermined electric potential provided at a drain of the resettransistor 18, e.g., a power voltage VDD, is transmitted to the floatingdiffusion region FD.

The select transistor 19 selects a pixel P to be read in a row unit. Theselect transistor 19 may be composed of one MOS transistor that isdriven by the bias (i.e., row select signal) provided from a row selectline SEL(i). When the select transistor 19 is turned on by the biasprovided from the row select line SEL(i), a predetermined electricpotential provided at a drain of the select transistor 19, e.g., thepower voltage VDD, is transmitted to the drain region of the drivetransistor 17.

The transfer line TX(i) to apply the bias to the charge transfertransistor 15, the reset line RX(i) to apply the bias to the resettransistor 18, and the row select line SEL(i) to apply the bias to theselect transistor 19 may be arranged in a substantially parallelextension with each other in a row direction.

FIGS. 3 and 4 illustrate a structure around the photoelectric transistor11 of FIG. 2. The photoelectric transistor 11 of FIG. 2 may correspondto a first photoelectric device 110 of FIG. 4.

Referring to FIGS. 3 and 4, the image sensor according to some exemplaryembodiments includes a substrate 100, a first photoelectric device 110,a boundary isolation film 130, an inner reflection pattern film 150, afirst fixed charge film 160, a first anti-reflection film 170, a firstlower planarizing film 180, a first side anti-reflection film 190, aninfrared filter 200, a first upper planarizing film 210, a first microlens 220, and a first protection film 230.

The substrate 100 may include a first surface 100 a and a second surface100 b opposite each other. The first surface 100 a of the substrate 100may be a front surface of the substrate 100, e.g., a bottom surfacefurthest from where light is incident on the image sensor, and thesecond surface 100 b of the substrate may be a back side of thesubstrate 100, e.g., a top surface closest to where light is incident onthe image sensor. However, exemplary embodiments are not limited to theexample given above.

For example, the substrate 100 may use a P-type or an N-type bulksubstrate, or may use a P-type or an N-type epitaxial layer grown on theP-type bulk substrate, or may use a P-type or an N-type epitaxial layergrown on the N-type bulk substrate. Further, a substrate other than asemiconductor substrate, such as an organic plastic substrate and so on,may also be used for the substrate 100.

A first sensing region S1 may be formed within the substrate 100.Specifically, the first sensing region S1 may be a region where theincident infrared light is sensed with the infrared filter 200. Thefirst sensing region S1 may be defined by the boundary isolation film130 which will be explained below.

The first photoelectric device 110, e.g., a photodiode, is formed withinthe substrate 100 of the first sensing region S1. The firstphotoelectric device 110 may be formed near the first surface 100 a ofthe substrate 100, although exemplary embodiments are not limited to anyspecific example only. The first photoelectric device 110 may be thephototransistor 11 of FIG. 2, i.e., the photodiode, the phototransistor,the photogate, the pinned-type photodiode or a combination thereof.

The boundary isolation film 130 may be formed within the substrate 100.The boundary isolation film 130 may define the first sensing region S1within the substrate 100. The boundary isolation film 130 may be formedon an edge of the first sensing region S1. Due to the presence of theboundary isolation film 130, the first sensing region S1 may be definedto be a closed space. A plane cross-sectional shape of the boundaryisolation film 130 may be a closed curved line in a loop shape.

The boundary isolation film 130 may be formed within a boundaryisolation trench 120. The boundary isolation trench 120 may be formed byetching in a depth direction into the substrate 100. The boundaryisolation trench 120 may be formed in the second surface 100 b of thesubstrate 100, and may extend in direction toward the first surface 100a. The boundary isolation trench 120 may not reach the first surface 100a of the substrate 100.

In an example, a depth of the boundary isolation trench 120 may be lessthan a depth at which the first photoelectric device 110 is positioned,e.g., a bottom surface of the boundary isolation trench 120 may befurther from the first surface 100 a than a top surface of the firstphotoelectric device 110. This is to prevent damage to the firstphotoelectric device during formation of the boundary isolation trench120. However, exemplary embodiments are not limited to the example givenabove.

In the image sensor according to some embodiments, a depth of theboundary isolation trench 120 may become deeper than a depth at whichthe first photoelectric device 110 is positioned, when the boundaryisolation trench 120 is formed at a sufficient horizontal distance awayfrom the first photoelectric device 110.

A side or lateral surface of the boundary isolation trench 120 may havea tapered shape, as illustrated in FIG. 4. Specifically, a width of theboundary isolation trench 120 may gradually decrease in a downwarddirection, e.g., towards the first surface 100 a, and may graduallyincrease in an upward direction, e.g., towards the second surface 100 b.However, exemplary embodiments are not limited to the example givenabove.

As illustrated in drawings, the boundary isolation trench 120 may befilled with the fixed charge film 160 and the first anti-reflection film170 formed on the fixed charge film 160, to form the boundary isolationfilm 130, which will be described below. Alternatively, the boundaryisolation trench 120 may be filled with one material.

As shown in FIG. 4, the boundary isolation film 130 may include thefixed charge film 160 and the first anti-reflection film 170. Forexample, the boundary isolation film 130 may include at least one ofsilicon oxide, silicon nitride, silicon oxynitride, or a low-kdielectric material with a smaller dielectric constant than siliconoxide. For example, the low-k dielectric material may include flowableoxide (FOX), tonen silazene (TOSZ), undoped silica glass (USG),borosilica glass (BSG), phosphosilica glass (PSG), borophosphosilicaglass (BPSG), plasma enhanced tetraethyl orthosilicate (PETEOS),fluoride silicate glass (FSG), carbon doped silicon oxide (CDO),xerogel, aerogel, amorphous fluorinated carbon, organo silicate glass(OSG), parylene, bis-benzocyclobutenes (BCB), SILK, polyimide, porouspolymeric material, or a combination thereof, but not limited thereto.

An inner reflection pattern trench 140 may be formed by etching in adepth direction into the substrate 100. The inner reflection patterntrench 140 may be formed in the second surface 100 b of the substrate100, and may extend in a direction toward the first surface 100 a. Theinner reflection pattern trench 140 may not reach the second surface 100b of the substrate 100.

In an example, a depth of the inner reflection pattern trench 140 may beless than a depth at which the first photoelectric device 110 ispositioned. Thus, damage to the first photoelectric device 110 duringformation of the inner reflection pattern trench 140 may be prevented.

A depth of the inner reflection pattern trench 140 may be shallower thanthe boundary isolation trench 120, e.g., a bottom surface of the innerreflection pattern trench 140 trench may be further from the firstsurface 100 a than a bottom surface of the boundary isolation trench120. However, exemplary embodiments are not limited to the example givenabove. A depth of the inner reflection pattern trench 140 may be sameas, or deeper than, the boundary isolation trench 120.

When a depth of the boundary isolation trench 120 increases so as tonearly approach a depth of the first photoelectric device 110, and whena depth of the inner reflection pattern trench 140 is same as a depth ofthe boundary isolation trench 120, the first photoelectric device 110may be exposed to damage. Accordingly, in an example, a depth of theinner reflection pattern trench 140 may be shallower than a depth of theboundary isolation trench 120.

In the image sensor according to some exemplary embodiments, when adepth of the boundary isolation trench 120 does not approach the firstphotoelectric device 110, a depth of the inner reflection pattern trench140 may be the same level as the boundary isolation trench 120. Becausethe method enables simultaneous formation of the boundary isolationtrench 120 and the inner reflection pattern trench 140 with one etchprocess, fabricating cost of the image sensor according to someexemplary embodiments may be minimized and waste of the process may alsobe saved. Further, yield rate of the image sensor may be enhanced asdifficulty of the process is decreased.

The inner reflection pattern film 150 may entirely fill the innerreflection pattern trench 140. Accordingly, when the inner reflectionpattern film 150 and the boundary isolation film 130 are not connected,e.g., upper surfaces of the fixed charge film 160 and the firstanti-reflection film 170 do not extend over the second surface 100 b,the inner reflection pattern film 150 may be the same level as thesecond surface 100 b of the substrate 100. The same may apply to theboundary isolation film 130. That is, an upper surface of the boundaryisolation film 130, the second surface 100 b of the substrate 100, andan upper surface of the inner reflection pattern film 150 may be flushwith one another.

The inner reflection pattern film 150 may be formed within the firstsensing region S1, e.g., may overlap the first sensing region in thevertical direction, e.g., a light incident direction. The innerreflection pattern film 150 may be aligned with a center of the firstsensing region S1. The inner reflection pattern film 150 may partitionthe first sensing region S1 into a plurality of regions. The innerreflection pattern film 150 may be in contact with the boundaryisolation film 130. Accordingly, the inner reflection pattern film 150and the boundary isolation film 130 may be connected to each other, thusisolating a plurality of regions in a horizontal cross section.

Unlike the illustration, the inner reflection pattern film 150 and theboundary isolation film 130 may not be in contact with each other in theimage sensor according to some exemplary embodiments. That is, the innerreflection pattern film 150 may have a shape such that the innerreflection pattern film 150 is surrounded with the boundary isolationfilm 130 defining the first sensing region S1 on the horizontal crosssection, but not in contact with each other.

The inner reflection pattern film 150 may be filled with the fixedcharge film 160 and the first anti-reflection film 170, like theboundary isolation film 130. However, exemplary embodiments are notlimited to the example given above. The inner reflection pattern film150 may be filled with one material. In this case, the fixed charge film160 and the first anti-reflection film 170 may be formed on the innerreflection pattern film 150.

For example, the inner reflection pattern film 150 may include, forexample, at least one of silicon oxide, silicon nitride, siliconoxynitride, or a low-k dielectric material with a smaller dielectricconstant than silicon oxide.

The first fixed charge film 160 may be formed on the second surface 100b of the substrate 100, a surface (lateral surfaces and bottom surface)of the boundary isolation trench 120, and a surface (lateral surfacesand bottom surface) of the inner reflection pattern trench 140. Thefirst fixed charge film 160 may be formed on an entire surface or aportion of the second surface 100 b of the substrate 100.

The first fixed charge film 160 may be formed to be a P+ type, when thefirst photoelectric device 110 (e.g., the photodiode 11) formed on apixel region is an N type. That is, the first fixed charge film 160 mayreduce dark current by reducing electron-hole pair (EHP) generatedthermally in the second surface 100 b of the substrate 100. According tocases, the first fixed charge film 160 may be omitted.

The first fixed charge film 160 may include, e.g., a metal oxide film ora metal nitride film, in which the metal may include hafnium (Hf),aluminum (Al), zirconium (Zr), tantalum (Ta), and titanium (Ti).Further, the first fixed charge film 160 may include at least one oflanthanum (La), praseodymium (Pr), cerium (Ce), neodymium (Nd),promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium(Tb), dysprosium (Dy), holmium (Ho), thulium (Tm), ytterbium (Yb),lutetium (Lu), and yttrium (Y). Further, the first fixed charge film 160may be formed of a hafnium oxynitride film or an aluminum oxynitridefilm.

The first fixed charge film 160 is illustrated as a single-layered filmin the drawing. However, it may be a stack structure combining two ormore films formed of a same material or different materials from eachother.

The first anti-reflection film 170 may be formed on the first fixedcharge film 160. The first anti-reflection film 170 may entirely fillthe boundary isolation trench 120 and the inner reflection patterntrench 140. The first anti-reflection film 170 may reduce or preventreflection of the external incident light. The first anti-reflectionfilm 170 may include a material having a different refractive index fromthe first fixed charge film 160. For example, the first anti-reflectionfilm 170 may be formed of an insulating film such as a silicon oxidefilm, a silicon nitride film, a silicon oxynitride film, resin, acombination thereof, or a stack thereof.

Double-layered configuration of the first fixed charge film 160 and thefirst anti-reflection film 170 with different refractive indexes fromeach other may serve to prevent reflection. Accordingly, reflection ofthe incident light on the second surface 100 b of the substrate 100 maybe reduced or prevented.

The material/thickness of the first anti-reflection film 170 may bevaried according to a wavelength of the light used in photo process. Forexample, a silicon oxide film with a thickness from about 50 Å to about200 Å and a silicon nitride film with a thickness from about 300 Å toabout 500 Å may be stacked and used as the first anti-reflection film170. However, exemplary embodiments are not limited to the example givenabove.

The first lower planarizing film 180 may be formed on the firstanti-reflection film 170. For example, the first lower planarizing film180 may include at least one of a silicon oxide film-based material, asilicon nitride film-based material, resin or a combination thereof.

The first lower planarizing film 180 may be used as a buffer film toprevent damage of the substrate 100 in a patterning process for forminga pad (not illustrated) in the non-pixel region.

The first lower planarizing film 180 may include a silicon oxidefilm-based material, a silicon nitride film-based material, a resin, ora combination thereof. For example, a silicon oxide film with athickness from about 3,000 Å to about 8,000 Å may be used as the firstlower planarizing film 180. However, exemplary embodiments are notlimited to the example given above.

The infrared filter 200 may be formed on the first lower planarizingfilm 180. The infrared filter 200 may filter out wavelengths others thanthe infrared light among the incident light. Accordingly, the light thatpasses through the infrared filter 200 is infrared light. The lightpassing through the infrared filter 200 may pass through the structuresbelow and reach the first photoelectric device 110. The firstphotoelectric device 110 may generate electric current with the incidentlight.

The first side anti-reflection film 190 may be formed on the first lowerplanarizing film 180. The first side anti-reflection film 190 mayoverlie a portion of the first lower planarizing film 180. The firstside anti-reflection film 190 may overlap the boundary isolation film130 in a vertical direction. That is, the first side anti-reflectionfilm 190 may be on an edge of the first sensing region S1.

The first side anti-reflection film 190 may be disposed on a sidesurface of the infrared filter 200. Specifically, the infrared filter200 may overlie a side surface and an upper surface of the first sideanti-reflection film 190. That is, a height of an upper surface of thefirst side anti-reflection film 190 may be lower than a height of anupper surface of the infrared filter 200.

The first side anti-reflection film 190 may reduce or prevent reflectionor scattering of the incident light to the side surface when passingthrough the infrared filter 200. That is, the first side anti-reflectionfilm 190 may prevent photons reflected and scattered from an interfaceof the infrared filter 200 and the first lower planarizing film 180 frommoving to another sensing region. Because the first side anti-reflectionfilm 190 operates at the interface as descried above, the first sideanti-reflection film 190 may cover only a portion of the side surface ofthe infrared filter 200.

The first side anti-reflection film 190 may include a metal. The firstside anti-reflection film 190 may include at least one of tungsten (W),aluminum (Al) and copper (Cu), for example.

The first upper planarizing film 210 may be formed flat on the infraredfilter 200. For example, the first upper planarizing film 210 mayinclude at least one of a silicon oxide film-based material, a siliconnitride film-based material, resin or a combination thereof. Althoughthe first upper planarizing film 210 is illustrated as a single-layeredfilm, this is provided only for convenience of explanation and thepresent disclosure is not limited hereto.

Although FIG. 4 illustrates by way of example that the first upperplanarizing film 210 and the first lower planarizing film 180 are on anupper surface and a lower surface of the infrared filter 200,respectively, exemplary embodiments may not be limited hereto. Forexample, the planarizing film may be only on a lower surface of theinfrared filter 200 or only on an upper surface of the infrared filter200. Alternatively, the planarizing film may be absent on both of theupper surface and the lower surface of the infrared filter 200.

The first micro lens 220 may be framed on the first upper planarizingfilm 210. The first micro lens 220 may have a convex upward shape, asillustrated. The convex shape of the first micro lens 220 mayconcentrate the incident light to the first sensing region S1.

The first micro lens 220 may be formed of an organic material such asphotoresist PR. However, exemplary embodiments are not limited to theexamples provided above. Accordingly, the first micro lens 220 may beformed by using an inorganic material. Formation of the first micro lens220 with an organic material may involve, for example, formation of thefirst micro lens 220 by forming an organic material pattern on the firstupper planarizing film 210 and performing annealing process. Theannealing process may cause the organic material pattern to be changedinto a shape of the first micro lens 220.

The first protection film 230 may be formed with a certain thicknessalong a surface of the first micro lens 220. The first protection film230 may be an inorganic oxide film. For example, a silicon oxide (SiO₂)film, a titanium oxide (TiO₂) film, a zirconium oxide (ZrO₂) film, ahafnium oxide (HfO₂) film, a stack thereof, and a combination thereofmay be used. Specifically, for the first protection film 230, lowtemperature oxide (LTO), which is one type of the silicon oxide film,may be used. With utilization of the LTO, damage on the underlying filmsmay be reduced because the LTO is fabricated at low temperature (about100° C.-200° C.). Further, the LTO is amorphous and thus has a smoothsurface, which may minimize reflection/refraction/scattering of theincident light.

Being formed of organic material, the first micro lens 220 may bevulnerable to external impact. Accordingly, the first protection film230 may protect the first micro lens 220 from external impact. Further,there may be a certain space between the neighboring micro lenses, andthe first protection film 230 may fill such space.

By filling the space between the neighboring micro lens and the firstmicro lens 220, the incident light concentrating capability may beincreased. Filling the space as described above may reducereflection/refraction/scattering of the incident light arriving at thespace between the neighboring micro lens and the first micro lens 220.

Referring to FIG. 5, the image sensor according to some exemplaryembodiments may convert the infrared light into electric current withthe infrared filter 200. In principle, the infrared light has a longerwavelength than visible light and, accordingly, has a longer penetratingdepth into silicon. Accordingly, a length of a substrate of the imagesensor using other RGB filters may be significantly shorter with respectto the infrared filter. Accordingly, the quantum efficiency (QE) of thefirst sensing region S1 according to the infrared filter may bedecreased. If the length of the substrate 100 is increased in order toprevent such QE loss, the sensing region for sensing the visible lighthaving other short wavelengths may have increased blooming risk.

Accordingly, in an image sensor according to some exemplary embodiments,the length of the substrate 100 used with the infrared sensor is thesame as that for use with visible light, e.g., RGB filter, and theincident infrared light 240 is reflected against the boundary isolationfilm 130 and the inner reflection pattern film 150 so as to beconcentrated on the first photoelectric device 110. That is, the innerreflection pattern film 150 may effectively shorten silicon penetrationdepth only in the first sensing region S1 where the infrared filter 200is positioned, differently from the other sensing regions.

Hereinbelow, an image sensor according to some exemplary embodimentswill be described with reference to FIG. 6. In the followingdescription, description that overlaps the exemplary embodiments alreadyprovided above will not be described or described as brief as possiblefor the sake of brevity.

FIG. 6 is a layout diagram provided to explain an image sensor accordingto some exemplary embodiments. Referring to FIG. 6, the image sensoraccording to some exemplary embodiments may include an inner reflectionpattern film 151.

The inner reflection pattern film 151 may have a plane shape which isnot in contact with the boundary isolation film 130. The innerreflection pattern film 151 may isolate the first sensing region S1 intoa rectangle region defined with the inner reflection pattern film 151and a surrounding region thereof. As a result, when the incidentinfrared light entering into the two regions are reflected against theinner reflection pattern films 151 or the inner reflection pattern film151 and the boundary isolation film 130, an effect of shortenedeffective silicon penetration depth may be obtained. Specifically, dueto a small crisscross-shaped pattern formed on an edge of the rectangle,reflection from the neighboring spaces may be further strengthened andQE damage may be significantly reduced.

Hereinbelow, an image sensor according to some exemplary embodimentswill be described with reference to FIG. 7. In the followingdescription, description that overlap the exemplary embodiments alreadyprovided above will not be described or described as brief as possiblefor the sake of brevity.

FIG. 7 is a layout diagram provided to explain an image sensor accordingto some exemplary embodiments. Referring to FIG. 7, the image sensoraccording to some exemplary embodiments may include an inner reflectionpattern film 152.

The inner reflection pattern film 152 may have a plane shape which isnot in contact with the boundary isolation film 130. The innerreflection pattern film 152 may isolate the first sensing region S1 intoa triangle region defined with the inner reflection pattern film 152 anda surrounding region thereof. As a result, as the incident infraredlight entering into the two regions are reflected against the innerreflection pattern films 152 or the inner reflection pattern film 152and the boundary isolation film 130, an effect of a shortened effectivesilicon penetration depth may be obtained. Specifically, due to a smallcrisscross-shaped pattern formed on an edge of the triangle, reflectionfrom the peripheral spaces may be further strengthened and QE damage maybe significantly reduced.

Hereinbelow, an image sensor according to some exemplary embodimentswill be described with reference to FIG. 8. In the followingdescription, description that overlaps the exemplary embodiments alreadyprovided above will not be described or described as brief as possiblefor the sake of brevity.

FIG. 8 is a layout diagram provided to explain an image sensor accordingto some exemplary embodiments. Referring to FIG. 8, the image sensoraccording to some exemplary embodiments may include an inner reflectionpattern film 153.

The inner reflection pattern film 153 may have a plane shape which isnot in contact with the boundary isolation film 130. The innerreflection pattern film 153 may isolate the first sensing region S1 intoa rectangle region defined with the inner reflection pattern film 153and a surrounding region thereof. As a result, as the incident infraredlight entering into the two regions are reflected against the innerreflection pattern films 153 or the inner reflection pattern film 153and the boundary isolation film 130, an effect of a shortened effectivesilicon penetration depth may be obtained. Specifically, because an edgeof the rectangle is not formed with another pattern, the area where theincident light of the sensing region penetrates is increased and imagesensing efficiency may thus be enhanced.

A shape of the inner reflection pattern film 150 may be freely modifiedaccording to purpose and characteristics of the image sensor, asexemplified in the above embodiments of FIGS. 6 to 8.

Hereinbelow, an image sensor according to some exemplary embodimentswill be described with reference to FIG. 9. In the followingdescription, description that overlaps the exemplary embodiments alreadyprovided above will not be described or described as brief as possiblefor the sake of brevity.

FIG. 9 is a cross-sectional view provided to explain an image sensoraccording to some exemplary embodiments. Referring to FIG. 9, the imagesensor according to some exemplary embodiments may additionally includean insulating structure 300.

The insulating structure 300 may be formed on the first surface 100 a ofthe substrate 100. That is, the insulating structure 300 may be formedon a front side of the substrate 100. The insulating structure 300 mayinclude an insulating film 320, a gate structure 310, and a wirestructure 330.

For example, the insulating film 320 may include at least one of asilicon oxide film, a silicon nitride film, a silicon oxynitride film, alow-k dielectric material, and a combination thereof. The insulatingfilm 320 may overlie and surround the gate structure 310 and the wirestructure 330 which will be described below. That is, the insulatingfilm 320 may serve to insulate the gate structure 310 and the wirestructure 330 from each other.

The insulating structure 310 may be on the first surface 100 a of thesubstrate 100. As illustrated in FIG. 2, the gate structure 310 may be,for example, a gate of the charge transfer transistor 15, a gate of thereset transistor 18, a gate of the select transistor 19, a gate of thedrive transistor 17, and so on.

Although FIG. 9 illustrates that the gate structure 310 is formed on thefirst surface 100 a of the substrate 100, exemplary embodiments are notlimited to any specific example only. Accordingly, the gate structure310 may be a shape recessed or buried within the substrate 100 as well.

For example, the wire structure 330 may include aluminum (Al), copper(Cu), tungsten (W), cobalt (Co), ruthenium (Ru), and so on, but notlimited hereto.

The wire structure 330 may be forming in the first region S1 and includea plurality of sequentially stacked wires. Although FIG. 9 illustratesthe wire structure 330 with three sequentially-stacked layers, this isprovided only for convenience of explanation, and the exemplaryembodiments are not limited to any specific example only.

When the wire structure 330 is on the first surface 100 a of thesubstrate 100, an area where the incident light is penetrated into thesecond surface 100 b may be increased. Further, when the wire structure330 is positioned on the first surface 100 a of the substrate 100, theincident light is reflected against the wire structure 330 and directedback to the first photoelectric device 110. Accordingly, efficiency ofthe image sensor may be maximized.

Hereinbelow, an image sensor according to some exemplary embodimentswill be described with reference to FIG. 10. In the followingdescription, description that overlaps the exemplary embodiments alreadyprovided above will not be described or described as brief as possiblefor the sake of brevity.

FIG. 10 is a cross-sectional view provided to explain an image sensoraccording to some exemplary embodiments. Referring to FIG. 10, the imagesensor according to some exemplary embodiments includes the boundaryisolation trench 121 and the boundary isolation film 131.

The boundary isolation trench 121 may connect the first surface 100 aand the second surface 100 b of the substrate 100. That is, the boundaryisolation trench 121 may penetrate fully through the substrate 100. Theboundary isolation trench 120 may completely surround a boundary of thefirst sensing region S1 in a vertical cross section as well as ahorizontal cross section.

The boundary isolation trench 121 may be formed with a Frontside DeepTrench Isolation (FDTI) process. This will be explained in detail below.

The boundary isolation film 131 may entirely fill the boundary isolationtrench 121. Accordingly, the boundary isolation film 131 may be exposedfrom the first surface 100 a and the second surface 100 b of thesubstrate 100. That is, the boundary isolation film 131 may include afirst surface same as the first surface 100 a of the substrate 100 and asecond surface same as the second surface 100 b of the substrate 100,e.g., be coplanar with both surface of the substrate 100.

The boundary isolation film 131 may extend longitudinally in a verticaldirection compared to the inner reflection pattern film 150. Because theinner reflection pattern film 150 overlaps the first photoelectricdevice 110 in the vertical direction, it may not penetrate through thesubstrate 100 like the boundary isolation film 131. However, exemplaryembodiments are not limited to the example given above.

Although it is illustrated that the boundary isolation trench 121 andthe boundary isolation film 131 have a constant width in the drawing, itmay not be limited hereto. The boundary isolation trench 121 and theboundary isolation film 131 may be formed in a tapered shape. That is, awidth of the boundary isolation trench 121 may be gradually reduced in adirection from the second surface 100 b toward the first surface 100 a.

The boundary isolation film 131 may include a conductive material suchas polysilicon, metal, and so on. In this case, the boundary isolationfilm 131 may secure a charge fixing function at an interface with thesubstrate 100 through a process of applying a negative voltage.Alternatively, a charge fixed region may be formed on the interfacethrough a doping process.

That is, in the image sensor according to some exemplary embodiments, ifthe inner reflection pattern film 150 does not overlap the firstphotoelectric device 110 in the vertical direction, the inner reflectionpattern film 150 may penetrate completely through the substrate 100 likethe boundary isolation film 131.

Hereinbelow, an image sensor according to some exemplary embodimentswill be described with reference to FIGS. 11 to 13. In the followingdescription, description that overlaps the exemplary embodiments alreadyprovided above will not be described or described as brief as possiblefor the sake of brevity.

FIG. 11 is a layout diagram provided to explain an image sensoraccording to some exemplary embodiments, and FIG. 12 is across-sectional view taken on line B-B′ of FIG. 11. FIG. 13 is a conceptview provided to explain operation when light is incident on the imagesensor shown in FIG. 12.

Referring to FIGS. 11 to 13, the image sensor according to someexemplary embodiments includes a second sensing region S2, a thirdsensing region S3, and a fourth sensing region S4, in addition to thefirst sensing region S1.

The first to fourth sensing regions S1-S4 may respectively have arectangular horizontal cross section. The adjacent sensing regions ofthe first to fourth sensing regions S1-S4 may again form a greaterrectangular horizontal cross section. Specifically, the second sensingregion S2 and the third sensing region S3 may be positioned respectivelyon different sides of the first sensing region S1, and the fourthsensing region S4 may be positioned in a diagonal direction. In otherwords, the first and second sensing regions S1 and S2 may be in contactwith third and fourth sensing regions S3 and S4, respectively, along asecond direction, and the first and third sensing regions S1 and S3 maybe in contact, respectively, with third and fourth sensing regions S3and S4 along a first direction, intersecting the second direction. Boththe first and second directions intersect a third direction, which isthe direction in which light is incident on the image sensor.

The first to fourth sensing regions S1-S4 may be partitioned with theboundary isolation film 130. That is, the boundary isolation film 130may be formed on a boundary of each of the first to fourth sensingregions S1-S4. Thus, the boundary isolation film 130 may have a largestrectangular outline, or a crisscross-shaped horizontal cross section inFIG. 11.

The second to fourth sensing regions S2-S4 may be sensing regions wherethe RGB filters are positioned respectively. That is, a blue colorfilter may be in the second sensing region S2, a green color filter maybe in the third sensing region S3, and a red color filter may be in thefourth sensing region S4. However, this is merely one of exemplaryembodiments. Accordingly, as long as the infrared filter 200 ispositioned in the first sensing region S1 and the RGB color filters arepositioned in the other regions, the position of each color filter maynot be limited.

The inner reflection pattern film 150 may be present only in the firstsensing region S1. The inner reflection pattern film 150 may reduce aneffective silicon penetration distance only in the first sensing regionS1 where the infrared filter 200 is present, and thus minimize QEdamage.

Referring to FIG. 12, the second sensing region S2 may include a secondphotoelectric device 1110, a second fixed charge film 1160, a secondanti-reflection film 1170, a second lower planarizing film 1180, asecond side anti-reflection film 1190, a blue color filter 1200, asecond upper planarizing film 1210, a second micro lens 1220, and asecond protection film 2230.

The second photoelectric device 1110 may be within the substrate 100 inthe second sensing region S2. The second fixed charge film 1160 isconnected to the first fixed charge film 160 and reduces the EHPgenerated thermally in the second surface 100 b of the substrate 100,thus reducing dark current.

The second anti-reflection film 1170 is connected to the firstanti-reflection film 170 and has a different refractive index from thesecond fixed charge film 1160, so that the second anti-reflection film1170 may reduce or prevent reflection of the external incident light.The second lower planarizing film 1180 may be connected to the firstlower planarizing film 180 to prevent the substrate 100 from beingdamaged in a patterning process.

The blue color filter 1200 may filter out wavelengths other than theblue color region of the visible light in the incident light. The lightpassed through the blue color filter 1200 may pass through the lowerstructures and reach the second photoelectric device 1110.

The second side anti-reflection film 1190 may be connected to a portionof the first side anti-reflection film 190. The second sideanti-reflection film 1190 may prevent the incident light passing throughthe blue color filter 1200 from reflecting or scattering to the sidesurface.

The second upper planarizing film 1210 may be connected to the firstupper planarizing film 210 to planarize height variations occurred dueto underlying structures. In an example, the planarizing film may bepresent only on a lower surface of the blue color filter 1200, or onlyon an upper surface of the blue color filter 1200. Alternatively, theplanarizing film may be absent on both of an upper surface and a lowersurface of the blue color filter 1200.

The second micro lens 1220 may be formed on the second upper planarizingfilm 1210. As illustrated, the second micro lens 1220 may have a convexupward shape. The second protection film 2230 may be formed with acertain thickness along a surface of the second micro lens 1220.Together with the first protection film 230, the second protection film2230 may fill between the first micro lens 220 and the second micro lens1220. As a result, the incident light concentrating capability may beenhanced.

Referring to FIG. 13, the first sensing region S1 has a shortenedeffective silicon penetration distance due to the inner reflectionpattern film 150 so that the incident infrared light 240 may reach thefirst photoelectric device 110. In the second sensing region S2, theincident light 1240 passed through the blue color filter 1200 may reachthe second photoelectric device 1110 with a regular, e.g.,non-shortened, length.

The image sensor according to some exemplary embodiments can maximizephotoelectric efficiency with the substrate 100 having a same depth withrespect to the light of different wavelengths and effective siliconpenetration distances.

Hereinbelow, an image sensor according to some exemplary embodimentswill be described with reference to FIG. 14. In the followingdescription, description that overlaps the exemplary embodiments alreadyprovided above will not be described or described as brief as possiblefor the sake of brevity.

FIG. 14 is a layout diagram provided to explain an image sensoraccording to some exemplary embodiments. Referring to FIG. 14, in theimage sensor according to some exemplary embodiments, the infraredfilter 200 may perform a role of both the infrared light filter and thered color filter in the first sensing region S1.

In the RGB filter having no infrared filter 200, a green color filtermay be the most needed filter. Accordingly, the green color filter nextto the blue color filter and the green color filter next to the redcolor filter (red/IR) may be disposed in the third sensing region S3 andthe second sensing region S2, respectively. Since the red color filterand the infrared filter 200 may be the adjacent wavelength regions toeach other, the Red/IR filter for filtering the two wavelength regionssimultaneously may be disposed in the first sensing region S1. As aresult, an area of the most-necessary region, i.e., the green colorfilter region, is increased, and the QE damage may be reduced orminimized, as in the red color filter and the infrared filter.

Hereinbelow, an image sensor according to some exemplary embodimentswill be described with reference to FIGS. 15 and 16. In the followingdescription, description overlapped with the exemplary embodimentsalready provided above will not be described or described as brief aspossible for the sake of brevity.

FIG. 15 is a layout diagram provided to explain an image sensoraccording to some exemplary embodiments. FIG. 16 is a cross-sectionalview taken on line C-C′ of FIG. 15.

Referring to FIGS. 15 and 16, in the image sensor according to someexemplary embodiments, the inner reflection pattern film 150 may beformed in the first sensing region S1, and the first to thirdsub-boundary isolation films 1150, 1151, 1152 may be formed in thesecond to fourth sensing regions S2-S4, respectively. Specifically, thefirst sub-boundary isolation film 1150 may be formed in the secondsensing region S2, the second sub-boundary isolation film 1151 may beformed in the third sensing region S3, and the third sub-boundaryisolation film 1152 may be formed in the fourth sensing region S4.

The first to third sub-boundary isolation films 1150, 1151, 1152 may bein contact with the boundary isolation film 130. The first to thirdsub-boundary isolation films 1150, 1151, 1152 may isolate the second tofourth sensing regions S2-S4 into a crisscross shape. However, exemplaryembodiments are not limited to the example given above, and the regionsmay be halved vertically according to some exemplary embodiments.

The first to third sub-boundary isolation films 1150, 1151, 1152 may beformed for an auto focusing function in the RGB color filter. That is,for the auto focusing function of quickly capturing a focal distance byusing a distance between two images in the right and the left on onepixel, the first to third sub-boundary isolation films 1150, 1151, 1152may partition one pixel, i.e., one sensing region, into a plurality ofpixels.

Referring to FIG. 16, the sub-boundary isolation trench 1140 may beformed by etching in a depth direction into the substrate 100. Thesub-boundary isolation trench 1140 may be formed on the second side 100b of the substrate 100, and may extend in a direction toward the firstside 100 a. The sub-boundary isolation trench 1140 may not reach thesecond side 100 b of the substrate 100.

In an example, a depth of the sub-boundary isolation trench 1140 may beless than a depth at which the first photoelectric device 110 ispositioned. This is to prevent damage of the second photoelectric device1110 during formation of the sub-boundary isolation trench 1140. A depthof the sub-boundary isolation trench 1140 may be deeper or shallowerthan a depth of the inner reflection pattern trench 140.

The first sub-boundary isolation film 1150 may be filled with the secondfixed charge film 1160 and the second anti-reflection film 1170.Likewise, the second and third sub-boundary isolation films 1151, 1152may be filled with a stack structure of the fixed charge film and theanti-reflection film.

Hereinbelow, an image sensor according to some exemplary embodimentswill be described with reference to FIG. 17. In the followingdescription, description that overlaps the exemplary embodiments alreadyprovided above will not be described or described as brief as possiblefor the sake of brevity.

FIG. 17 is a layout diagram provided to explain an image sensoraccording to some exemplary embodiments. Referring to FIG. 17, the imagesensor according to some exemplary embodiments may include the innerreflection pattern film 151 in the first sensing region S1, and includethe first to third sub-boundary isolation films 1150, 1151, 1152 in thesecond to fourth sensing regions S2-S4.

The first to third sub-boundary isolation films 1150, 1151, 1152 may bein contact with the boundary isolation film 130 to partition the secondto fourth sensing regions S2-S4 into a plurality of regions.Alternatively, the inner reflection pattern film 151 may not be incontact with the boundary isolation film 130 within the substrate 100and may not partition the first sensing region S1. (Of course, theanti-reflection film and the fixed charge film may be connected to eachother above the substrate 100, but the expression ‘not in contact’ asused herein means that each of the trenches do not contact within thesubstrate 100.) The inner reflection pattern film 151 may be also incontact with the boundary isolation film 130 (within the substrate 100),and may partition the first sensing region S1.

This contact arises due to different functions of the first to thirdsub-boundary isolation films 1150, 1151 1152 and the inner reflectionpattern film 151. The first to third sub-boundary isolation films 1150,1151, 1152 may partition the sensing regions for the purpose of autofocusing, but the inner reflection pattern film 151 may simply reflectthe incident infrared light so as to minimize the QE damage.Accordingly, a degree of freedom with respect to a shape of the innerreflection pattern film 151 may be higher than a degree of freedom withrespect to shapes of the first to third sub-boundary isolation films1150, 1151, 1152.

Hereinbelow, a method for fabricating an image sensor according to someexemplary embodiments will be explained with reference to FIGS. 12 and18 to 24. In the following description, description that overlaps theexemplary embodiments already provided above will not be described ordescribed as brief as possible for the sake of brevity. FIGS. 18 to 24are views illustrating intermediate stages of fabrication, provided toexplain a method for fabricating an image sensor according to someexemplary embodiments.

Referring first to FIG. 18, the substrate 100 is provided. The substrate100 may include the first surface 100 a and the second surface 100 bopposite each other. The first surface 100 a of the substrate 100 may bea front side, and the second surface 100 b of the substrate 100 may be aback side. The substrate 100 may include the first photoelectric device110 and the second photoelectric device 1110 therein. The firstphotoelectric device 110 may be positioned in the first sensing regionS1 of the substrate 100, and the second photoelectric device 1110 may bepositioned in the second sensing region S2.

Next, referring to FIG. 19, the insulating structure 300 is formed onthe first surface 100 a. The insulating structure 300 may be formed onthe first side 100 a of the substrate 100. That is, the insulatingstructure 300 may be formed on the front side of the substrate 100. Theinsulating structure 300 may include an insulating film 320, a gatestructure 310, and a wire structure 330.

The insulating film 320 may overlie and surround the gate structure 310and the wire structure 330 which will be described below. That is, theinsulating film 320 may serve to insulate between the gate structure 310and the wire structure 330.

The insulating structure 300 may be on the first side 100 a of thesubstrate 100. As illustrated in FIG. 2, the gate structure 310 may be,e.g., a gate of the charge transfer transistor 15, a gate of the resettransistor 18, a gate of the select transistor 19 a gate of the drivetransistor 17, and so on. The wire structure 330 may be formed in thefirst region S1 and include a plurality of sequentially stacked wires.

Next, referring to FIG. 20, the substrate 100 is flipped or inverted sothat the second surface 100 b faces upward. Accordingly, with respect tocurrent state of the substrate 100, the first side 100 a may be a lowersurface and the second surface 100 b may be an upper surface.Accordingly, the insulating structure 300 may be positioned under thesubstrate 100.

Next, referring to FIG. 21, a first fixed charge film 160 and a secondfixed charge film 1160 may be formed on the boundary isolation trench120 and the inner reflection pattern trench 140. The first fixed chargefilm 160 may be formed along the second surface 100 b of the substrate100 and surfaces of the boundary isolation trench 120 and the innerreflection pattern trench 140. The first fixed charge film 160 may fillonly a portion of the boundary isolation trench 120 and the innerreflection pattern trench 140. In an example, the inner reflectionpattern film 150 is formed in the first sensing region S1, but there isno film within the sensing region that is formed in the second sensingregion S2.

Next, referring to FIG. 22, the first anti-reflection film 170 and thesecond anti-reflection film 1170 are formed. The first anti-reflectionfilm 170 and the second anti-reflection film 1170 may be formed on thefirst fixed charge film 160 and the second fixed charge film 1160,respectively. The first anti-reflection film 170 and the secondanti-reflection film 1170 may reduce or prevent reflection of theexternal incident light.

Next, the first lower planarizing film 180 and the second lowerplanarizing film 1180 are formed. The first lower planarizing film 180and the second lower planarizing film 1180 may include, for example, atleast one of a silicon oxide film-based material, a silicon nitridefilm-based material, resin, or a combination thereof.

Next, referring to FIG. 23, the infrared filter 200, the blue colorfilter 1200, the first side anti-reflection film 190 and the second sideanti-reflection film 1190 are formed. The infrared filter 200 may filterout wavelengths other than infrared light in the incident light. Theblue color filter 1200 may filter out wavelengths except for the bluecolor region of the visible light in the incident light.

The first side anti-reflection film 190 and the second sideanti-reflection film 1190 may cover a portion of the infrared filter 200and the blue color filter 1200 from a lateral surface of the infraredfilter 200 and the blue color filter 1200, respectively. The first sideanti-reflection film 190 and the second side anti-reflection film 1190may include, for example, tungsten (W).

Next, referring to FIG. 24, the first upper planarizing film 210 and thesecond upper planarizing film 1210 are formed. The first upperplanarizing film 210 may be formed on the infrared filter 200. Thesecond upper planarizing film 1210 may be formed flat on the blue colorfilter 1200. The second upper planarizing film 1210 and the second upperplanarizing film 1210 may include, e.g., at least one of a silicon oxidefilm-based material, a silicon nitride film-based material, resin or acombination thereof.

Next, referring to FIG. 12, a first micro lens 220 and a second microlens 1220 are formed. In an example, although FIG. 12 does notspecifically illustrate an insulating structure 300, it is assumedherein that the insulating structure 300 of FIG. 11 is provided.

The first micro lens 220 and the second micro lens 1220 may be formed ofan organic material such as photoresist PR. Formation of the first microlens 220 and the second micro lens 1220 with an organic material mayinvolve, for example, formation of the first micro lens 220 and thesecond micro lens 1220 by forming an organic material pattern on thefirst upper planarizing film 210 and the second upper planarizing film1210 and performing annealing process. The annealing process may causethe organic material pattern to be changed into a form of the firstmicro lens 220 and the second micro lens 1220.

Next, the first protection film 230 and the second protection film 2230may be formed on the first micro lens 220 and the second micro lens1220, respectively. In this case, the first protection film 230 and thesecond protection film 2230 may be an inorganic oxide film.

Hereinbelow, a method for fabricating an image sensor according to someexemplary embodiments will be explained with reference to FIGS. 18 and25 to 28. In the following description, description that overlaps theexemplary embodiments already provided above will not be described ordescribed as brief as possible for the sake of brevity.

FIGS. 25 to 28 are views illustrating stages in method for fabricatingan image sensor according to some exemplary embodiments. The descriptionabout the embodiment of FIG. 18, which may be identical, may not beredundantly explained below.

Next, referring to FIG. 25, the boundary isolation film 131 is formed.The boundary isolation film 131 may be formed on the first surface 100 awith the FDTI process. The boundary isolation trench 121 may penetratethrough the first surface 100 a and the second surface 100 b.

The boundary isolation film 131 may entirely fill the boundary isolationtrench 121. Accordingly, the boundary isolation film 131 may be exposedfrom the first side 100 a and the second side 100 b of the substrate100. That is, the boundary isolation film 131 may include a first sidesame as the first side 100 a of the substrate 100 and a second side sameas the second side 100 b of the substrate 100.

The boundary isolation film 131 may be filled with polysilicon or ametal. The boundary isolation film 131 may allow charge to be fixed onthe interface of the substrate 100 and the boundary isolation film 131through a process of applying a negative voltage.

Alternatively, a region fixed with charge may be formed by performing adoping process on sidewalls of the boundary isolation trench 121 beforeformation of the boundary isolation film 131. Through the methodsdescribed above, the substrate 100 and the boundary isolation film 131may have different conductive types from each other, which may reducethe EHP generated thermally and reduce dark current.

Next, referring to FIG. 26, the insulating structure 300 is formed onthe first side 100 a. The insulating structure 300 may be formed on thefirst surface 100 a of the substrate 100 and the boundary isolation film131. That is, the insulating structure 300 may be formed on the frontside of the substrate 100. The insulating structure 300 may include aninsulating film 320, a gate structure 310, and a wire structure 330.

Next, referring to FIG. 27, the substrate 100 is inverted so that thesecond side 100 b is faced upward. Accordingly, with respect to currentstate of the substrate 100, the first surface 100 a may be a lowersurface and the second surface 100 b may be an upper surface.Accordingly, the insulating structure 300 may be positioned under thesubstrate 100 in the image sensor.

Next, referring to FIG. 28, the first fixed charge film 160 is formed onthe second side 100 b of the second sensing region S2 and a surface ofthe inner reflection pattern trench 140.

Next, referring to FIGS. 10 and 22 to 24, an upper structure is furtherformed. FIG. 10 is a view illustrating a first sensing region S1including the boundary isolation film 131, and FIGS. 22 to 24 are viewsillustrating that an upper structure is formed uniformly except that theboundary isolation film 130 is included instead of the boundaryisolation film 131.

Accordingly, in the first sensing region S1, the first anti-reflectionfilm 170, the first lower planarizing film 180, the infrared filter 200,the first side anti-reflection film 190, the first upper planarizingfilm 210, the first micro lens 220, and the first protection film 230may be formed in the first fixed charge film 160.

Likewise, in the second sensing region S2, the second anti-reflectionfilm 1170, the second lower planarizing film 1180, the blue color filter1200, the second side anti-reflection film 1190, the second upperplanarizing film 1210, the second micro lens 1220, and the secondprotection film 2230 may be formed in the second fixed charge film 1160.

By way of summation and review, one or more embodiments provide an imagesensor with improved operating characteristics and method forfabricating the same.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present invention asset forth in the following claims.

1.-31. (canceled)
 32. A image sensor including an infrared (IR) sensingregion, the IR sensing region comprising: a substrate having a topsurface and a bottom surface; a first boundary isolation trench having afirst length from the top surface and disposed at a first boundary ofthe IR sensing region; a first boundary isolation film filling the firstboundary isolation trench; a second boundary isolation trench having asecond length from the top surface and disposed at a second boundary ofthe IR sensing region; a second boundary isolation film filling thesecond boundary isolation trench; an inner reflection pattern filmhaving a third length from the top surface between the first boundaryisolation trench and the second boundary isolation trench; and aplanarizing film on the top surface, wherein the third length is shorterthan the first length, and wherein the planarizing film includes asilicon nitride.
 33. The image sensor of claim 32, wherein the firstboundary isolation film includes hafnium oxide.
 34. The image sensor ofclaim 33, wherein the first boundary isolation trench does not connectthe top surface and the bottom surface.
 35. The image sensor of claim33, wherein the first boundary isolation trench connects the top surfaceand the bottom surface.
 36. The image sensor of claim 35, furthercomprising a side anti-reflection film on the planarizing film.
 37. Theimage sensor of claim 36, wherein the side anti-reflection film includestungsten.
 38. The image sensor of claim 32, wherein the first boundaryisolation film includes aluminum oxide.
 39. The image sensor of claim38, wherein the first boundary isolation trench does not connect the topsurface and the bottom surface.
 40. The image sensor of claim 38,wherein the first boundary isolation trench connects the top surface andthe bottom surface.
 41. The image sensor of claim 40, further comprisinga side anti-reflection film on the planarizing film.
 42. The imagesensor of claim 41, wherein the side anti-reflection film includestungsten.
 43. A image sensor including an infrared (IR) sensing region,the IR sensing region comprising: a substrate having a top surface and abottom surface; a first boundary isolation trench having a first lengthfrom the top surface and disposed at a first boundary of the IR sensingregion a first boundary isolation film filling the first boundaryisolation trench; a second boundary isolation trench having a secondlength from the top surface and disposed at a second boundary of the IRsensing region; a second boundary isolation film filling the secondboundary isolation trench; an inner reflection pattern film having athird length from the top surface between the first boundary isolationtrench and the second boundary isolation trench; and a first planarizingfilm on the top surface, wherein the third length is shorter than thefirst length, and wherein the inner reflection pattern film includes ahafnium oxide.
 44. The image sensor of claim 43, further comprising asecond planarizing film on the first planarizing film.
 45. The imagesensor of claim 44, wherein the first boundary isolation trench does notconnect the top surface and the bottom surface.
 46. The image sensor ofclaim 44, wherein the first boundary isolation trench connects the topsurface and the bottom surface.
 47. The image sensor of claim 36,further comprising a micro-lens on the second planarizing film and aprotection film on the micro-lens.
 48. The image sensor of claim 47,wherein the protection film is a silicon oxide film.
 49. The imagesensor of claim 43, wherein the first planarizing film has a thicknessfrom about 3,000 angstroms to about 8,000 angstroms.